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University of Texas Rio Grande Valley

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Articles 541 - 570 of 832

Full-Text Articles in Astrophysics and Astronomy

Optimization Of Nanograv's Time Allocation For Maximum Sensitivity To Single Sources, Brian Christy, Ryan Anella, Andrea N. Lommen, Lee Samuel Finn, Richard S. Camuccio, Emma Handzo Oct 2014

Optimization Of Nanograv's Time Allocation For Maximum Sensitivity To Single Sources, Brian Christy, Ryan Anella, Andrea N. Lommen, Lee Samuel Finn, Richard S. Camuccio, Emma Handzo

Physics & Astronomy Faculty Publications

Pulsar timing arrays (PTAs) are a collection of precisely timed millisecond pulsars (MSPs) that can search for gravitational waves (GWs) in the nanohertz frequency range by observing characteristic signatures in the timing residuals. The sensitivity of a PTA depends on the direction of the propagating GW source, the timing accuracy of the pulsars, and the allocation of the available observing time. The goal of this paper is to determine the optimal time allocation strategy among the MSPs in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) for a single source of GW under a particular set of assumptions. We …

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A 24 Hr Global Campaign To Assess Precision Timing Of The Millisecond Pulsar J1713+0747, T. Dolch, M. T. Lam, J. Cordes, S. Chatterjee, C. Bassa, B. Bhattacharyya, D. J. Champion, I. Cognard, K. Crowter, Fredrick A. Jenet Oct 2014

A 24 Hr Global Campaign To Assess Precision Timing Of The Millisecond Pulsar J1713+0747, T. Dolch, M. T. Lam, J. Cordes, S. Chatterjee, C. Bassa, B. Bhattacharyya, D. J. Champion, I. Cognard, K. Crowter, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

The radio millisecond pulsar J1713+0747 is regarded as one of the highest-precision clocks in the sky and is regularly timed for the purpose of detecting gravitational waves. The International Pulsar Timing Array Collaboration undertook a 24 hr global observation of PSR J1713+0747 in an effort to better quantify sources of timing noise in this pulsar, particularly on intermediate (1.24 hr) timescales. We observed the pulsar continuously over 24 hr with the Arecibo, Effelsberg, GMRT, Green Bank, LOFAR, Lovell, Nancay, Parkes, and WSRT radio telescopes. The combined pulse times-of-arrival presented here provide an estimate of what sources of timing noise, excluding …

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Mapping Gravitational-Wave Backgrounds Using Methods From Cmb Analysis: Application To Pulsar Timing Arrays, Jonathan Gair, Joseph D. Romano, Stephen Taylor, Chiara M. F. Mingarelli Oct 2014

Mapping Gravitational-Wave Backgrounds Using Methods From Cmb Analysis: Application To Pulsar Timing Arrays, Jonathan Gair, Joseph D. Romano, Stephen Taylor, Chiara M. F. Mingarelli

Physics & Astronomy Faculty Publications

We describe an alternative approach to the analysis of gravitational-wave backgrounds, based on the formalism used to characterize the polarization of the cosmic microwave background. In contrast to standard analyses, this approach makes no assumptions about the nature of the background and so has the potential to reveal much more about the physical processes that generated it. An arbitrary background can be decomposed into modes whose angular dependence on the sky is given by gradients and curls of spherical harmonics. We derive the pulsar timing overlap reduction functions for the individual modes, which are given by simple combinations of spherical …

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Theoretical And Experimental Infrared Spectra Of Hydrated And Dehydrated Sulfonated Poly(Ether Ether Ketone), Jonathan Doan, Erin Kingston, Ian Kendrick, Kierstyn Anderson, Nicholas Dimakis, Philippe Knauth, Maria Luisa Di Vona, Eugene S. Smotkina Sep 2014

Theoretical And Experimental Infrared Spectra Of Hydrated And Dehydrated Sulfonated Poly(Ether Ether Ketone), Jonathan Doan, Erin Kingston, Ian Kendrick, Kierstyn Anderson, Nicholas Dimakis, Philippe Knauth, Maria Luisa Di Vona, Eugene S. Smotkina

Physics & Astronomy Faculty Publications

Time-dependent FT-IR spectra of sulfonated poly(ether ether ketone) during dehydration show diminishing 1081 cm−1 and 1023 cm−1 band intensities concurrent with the emergence and shifting of bands at 1362 cm−1 and 898 cm−1. Animations of density functional theory calculated normal modes enable assignment of the 1081 cm−1 and 1023 cm−1 bands as group modes that include a sulfonate exchange site with C3v local symmetry, while the 1362 cm−1 and 898 cm−1 bands are assigned as group modes that include an associated sulfonic acid with no local symmetry (C1). In contrast to analogously assigned Nafion group mode bands, the SPEEK C3v …

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First All-Sky Search For Continuous Gravitational Waves From Unknown Sources In Binary Systems, J. Aasi, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Sep 2014

First All-Sky Search For Continuous Gravitational Waves From Unknown Sources In Binary Systems, J. Aasi, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO science run and the second and third Virgo science runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ∼2; 254 h and a frequency- and period-dependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range …

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The Green Bank Northern Celestial Cap Pulsar Survey. I. Survey Description Data Analysis And Initial Results, Kevin Stovall, R. S. Lynch, Louis Percy Dartez, Anthony J. Ford, A. Garcia, J. Hinojosa, Fredrick A. Jenet, Sean Leake, Jose Guadalupe Martinez, Alberto Mata Aug 2014

The Green Bank Northern Celestial Cap Pulsar Survey. I. Survey Description Data Analysis And Initial Results, Kevin Stovall, R. S. Lynch, Louis Percy Dartez, Anthony J. Ford, A. Garcia, J. Hinojosa, Fredrick A. Jenet, Sean Leake, Jose Guadalupe Martinez, Alberto Mata

Physics & Astronomy Faculty Publications

We describe an ongoing search for pulsars and dispersed pulses of radio emission, such as those from rotating radio transients (RRATs) and fast radio bursts, at 350 MHz using the Green Bank Telescope. With the Green Bank Ultimate Pulsar Processing Instrument, we record 100 MHz of bandwidth divided into 4096 channels every 81.92 μs. This survey will cover the entire sky visible to the Green Bank Telescope (δ > -40°, or 82% of the sky) and outside of the Galactic Plane will be sensitive enough to detect slow pulsars and low dispersion measure (cm-3) millisecond pulsars (MSPs) with a 0.08 duty …

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Fast Radio Burst Discovered In The Arecibo Pulsar Alfa Survey, L. G. Spitler, J. M. Cordes, J. W.T. Hessels, D. R. Lorimer, M. A. Mclaughlin, S. Chatterjee, F. Crawford, J. S. Deneva, Fredrick Jenet Aug 2014

Fast Radio Burst Discovered In The Arecibo Pulsar Alfa Survey, L. G. Spitler, J. M. Cordes, J. W.T. Hessels, D. R. Lorimer, M. A. Mclaughlin, S. Chatterjee, F. Crawford, J. S. Deneva, Fredrick Jenet

Physics & Astronomy Faculty Publications

Recent work has exploited pulsar survey data to identify temporally isolated, millisecond-duration radio bursts with large dispersion measures (DMs). These bursts have been interpreted as arising from a population of extragalactic sources, in which case they would provide unprecedented opportunities for probing the intergalactic medium; they may also be linked to new source classes. Until now, however, all so-called fast radio bursts (FRBs) have been detected with the Parkes radio telescope and its 13-beam receiver, casting some concern about the astrophysical nature of these signals. Here we present FRB 121102, the first FRB discovery from a geographic location other than …

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Illustrations And Supporting Texts For Sound Standing Waves Of Air Columns In Pipes In Introductory Physics Textbooks, Liang Zeng, Chris Smith, G. Herold Poelzer, Jennifer Rodriguez, Edgar Corpuz, George Yanev Jul 2014

Illustrations And Supporting Texts For Sound Standing Waves Of Air Columns In Pipes In Introductory Physics Textbooks, Liang Zeng, Chris Smith, G. Herold Poelzer, Jennifer Rodriguez, Edgar Corpuz, George Yanev

Physics & Astronomy Faculty Publications

In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on the construct of meaningful learning from cognitive psychology and semiotics, a quasiexperimental study was conducted to investigate the comparative effectiveness of two alternative approaches to student understanding: a traditional textbook illustration approach versus a newly designed air molecule motion illustration approach. Thirty volunteer students from introductory physics classes were randomly …

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Detection And Estimation Of Unmodeled Narrowband Nonstationary Signals: Application Of Particle Swarm Optimization In Gravitational Wave Data Analysis, Soumya Mohanty Jul 2014

Detection And Estimation Of Unmodeled Narrowband Nonstationary Signals: Application Of Particle Swarm Optimization In Gravitational Wave Data Analysis, Soumya Mohanty

Physics & Astronomy Faculty Publications

The extraction of weak signals from instrumental noise is a critical task in ongoing searches for gravitational waves. A detection and estimation method, made feasible by Particle Swarm Optimization, is presented for a particularly challenging class of signals expected from astrophysical sources.

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Globular Cluster Simulations By Mocca Code, Dongming Jin Jul 2014

Globular Cluster Simulations By Mocca Code, Dongming Jin

Theses and Dissertations - UTB/UTPA

The MOCCA code is one of the most advanced codes that has the capacity to simulate a realistic sized star cluster with a full dynamical history including stellar evolution using Monte Carlo methods for the cluster evolution and the Fewbody code for scattering. The dynamical evolution of a cluster can result in the formation of many binary systems. Some of these binaries may be very close. Close double white dwarf binaries (double WDBs) may be promising gravitational wave sources. Our work uses MOCCA to simulate 90 globular clusters with different numbers of stars, binary fractions, metallicities and power-law indices of …

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Search For Gravitational Waves Associated With Γ-Ray Bursts Detected By The Interplanetary Network, J. Aasi, B. P. Abbott, Mario C. Diaz, S. R. Morriss, Soma Mukherjee, M. E. Normandin, Volker Quetschke, O. Puncken, Malik Rakhmanov, Karla E. Ramirez, Robert Stone Jun 2014

Search For Gravitational Waves Associated With Γ-Ray Bursts Detected By The Interplanetary Network, J. Aasi, B. P. Abbott, Mario C. Diaz, S. R. Morriss, Soma Mukherjee, M. E. Normandin, Volker Quetschke, O. Puncken, Malik Rakhmanov, Karla E. Ramirez, Robert Stone

Physics & Astronomy Faculty Publications

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005–2010 during LIGO’s fifth and sixth science runs and Virgo’s first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search …

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Methods And Results Of A Search For Gravitational Waves Associated With Gamma-Ray Bursts Using The Geo 600, Ligo, And Virgo Detectors, J. Aasi, B. P. Abbott, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Robert Stone, Cristina V. Torres Jun 2014

Methods And Results Of A Search For Gravitational Waves Associated With Gamma-Ray Bursts Using The Geo 600, Ligo, And Virgo Detectors, J. Aasi, B. P. Abbott, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Robert Stone, Cristina V. Torres

Physics & Astronomy Faculty Publications

In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz–1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO 600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyze GRB events with large sky localization uncertainties, for example the localizations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well localized, due to the corrections required for the difference in arrival time between detectors. …

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The Ninja-2 Project: Detecting And Characterizing Gravitational Waveforms Modelled Using Numerical Binary Black Hole Simulations, J. Aasi, B. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone Jun 2014

The Ninja-2 Project: Detecting And Characterizing Gravitational Waveforms Modelled Using Numerical Binary Black Hole Simulations, J. Aasi, B. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone

Physics & Astronomy Faculty Publications

The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave (GW) astrophysics communities. The purpose of NINJA is to study the ability to detect GWs emitted from merging binary black holes (BBH) and recover their parameters with next-generation GW observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete BBH hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a ‘blind injection challenge’ similar to that conducted in recent Laser …

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Arecibo Pulsar Survey Using Alfa. Iii. Precursor Survey And Population Synthesis, J. K. Swiggum, D. R. Lorimer, M. A. Mclaughlin, S. D. Bates, D. J. Champion, S. M. Ransom, A. Brazier, J. W.T. Hessels, D. J. Nice, Fredrick A. Jenet Jun 2014

Arecibo Pulsar Survey Using Alfa. Iii. Precursor Survey And Population Synthesis, J. K. Swiggum, D. R. Lorimer, M. A. Mclaughlin, S. D. Bates, D. J. Champion, S. M. Ransom, A. Brazier, J. W.T. Hessels, D. J. Nice, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo (32° ≲ ℓ ≲ 77° and 168° ≲ ℓ ≲ 214°) close to the Galactic plane (|b| ≲ 5°) for pulsars. The PALFA survey is sensitive to sources fainter and more distant than have previously been seen because of Arecibo's unrivaled sensitivity. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in ℓ and |b| ≲ 1°) …

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Search For Gravitational Wave Ringdowns From Perturbed Intermediate Mass Black Holes In Ligo-Virgo Data From 2005–2010, J. Aasi, B. P. Abbott, Matthew Benacquista, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, Cristina V. Torres May 2014

Search For Gravitational Wave Ringdowns From Perturbed Intermediate Mass Black Holes In Ligo-Virgo Data From 2005–2010, J. Aasi, B. P. Abbott, Matthew Benacquista, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, Cristina V. Torres

Physics & Astronomy Faculty Publications

We report results from a search for gravitational waves produced by perturbed intermediate mass black holes (IMBH) in data collected by LIGO and Virgo between 2005 and 2010. The search was sensitive to astrophysical sources that produced damped sinusoid gravitational wave signals, also known as ringdowns, with frequency 50 ≤ f0=Hz ≤ 2000 and decay timescale 0.0001 ≲ τ=s ≲ 0.1 characteristic of those produced in mergers of IMBH pairs. No significant gravitational wave candidate was detected. We report upper limits on the astrophysical coalescence rates of IMBHs with total binary mass 50 ≤ M=M⊙ ≤ 450 and component mass …

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Mri Characterization Of Cobalt Dichloride-N-Acetyl Cysteine (C4) Contrast Agent Marker For Prostate Brachytherapy, Tze Yee Lim, R. Jason Stafford, Rajat J. Kudchadker, Madhuri Sankaranarayanapillai, Geoffrey Ibbott, Arvind Rao, Karen S. Martirosyan, Steven J. Frank May 2014

Mri Characterization Of Cobalt Dichloride-N-Acetyl Cysteine (C4) Contrast Agent Marker For Prostate Brachytherapy, Tze Yee Lim, R. Jason Stafford, Rajat J. Kudchadker, Madhuri Sankaranarayanapillai, Geoffrey Ibbott, Arvind Rao, Karen S. Martirosyan, Steven J. Frank

Physics & Astronomy Faculty Publications

Brachytherapy, a radiotherapy technique for treating prostate cancer, involves the implantation of numerous radioactive seeds into the prostate. While the implanted seeds can be easily identified on a CT image, distinguishing the prostate and surrounding soft tissues is not as straightforward. Magnetic Resonance Imaging (MRI) offers superior anatomical delineation, but the seeds appear as dark voids and are difficult to identify, thus creating a conundrum. Cobalt dichloride-N-acetylcysteine (C4) has previously been shown to be promising as an encapsulated contrast agent marker. We performed spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) measurements of C4 solutions with varying cobalt dichloride …

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Experimental Observation Of Lasing Shutdown Via Asymmetric Gain, M. Chitsazi, S. Factor, J. Schindler, Hamidreza Ramezani, F. M. Ellis, T. Kottos Apr 2014

Experimental Observation Of Lasing Shutdown Via Asymmetric Gain, M. Chitsazi, S. Factor, J. Schindler, Hamidreza Ramezani, F. M. Ellis, T. Kottos

Physics & Astronomy Faculty Publications

Using a pair of coupled RLC cavities we experimentally demonstrate that amplification action can be tamed by a spatially inhomogeneous gain. Under specific conditions we observe the counterintuitive phenomenon of stabilization of the system even when the overall gain provided is increased. This behavior is directly related to lasing shutdown via asymmetric pumping, recently proposed in M. Liertzer et al. [Phys. Rev. Lett. 108, 173901 (2012)]. The analysis of other simple systems reveals the universal nature of the lasing shutdown phenomenon as having its roots in managing impedance matching.

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Optical Isolation Via Pt-Symmetric Nonlinear Fano Resonances, F. Nazari, N. Bender, Hamidreza Ramezani, M. K. Moravvej-Farshi, D. N. Christodoulides, T. Kottos Apr 2014

Optical Isolation Via Pt-Symmetric Nonlinear Fano Resonances, F. Nazari, N. Bender, Hamidreza Ramezani, M. K. Moravvej-Farshi, D. N. Christodoulides, T. Kottos

Physics & Astronomy Faculty Publications

We show that Fano resonances created by twoPT -symmetric nonlinear micro-resonators coupled to a waveguide, have line-shape and resonance position that depends on the direction of the incident light. We utilize these features in order to induce asymmetric transport, up to 47 dBs, in the optical C-window. Our theoretical proposal requires low input power and does not compromise the power or frequency characteristics of the output signal.

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Gravitational Waves From Known Pulsars: Results From The Initial Detector Era, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Walter Ortega Larcher, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Apr 2014

Gravitational Waves From Known Pulsars: Results From The Initial Detector Era, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Walter Ortega Larcher, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and …

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A Digital Backend For The Low Frequency All Sky Monitor, Louis Percy Dartez Apr 2014

A Digital Backend For The Low Frequency All Sky Monitor, Louis Percy Dartez

Theses and Dissertations - UTB/UTPA

The Low Frequency All Sky Monitor (LoFASM) is a distributed array of dipole antennas that are sensitive to radio frequencies from 10 to 88 MHz. The primary science goals of LoFASM are the detection and study of low-frequency radio transients, a high priority science goal as deemed by the National Research Council's decadal survey. LoFASM consists of antennas and front-end electronics that were originally developed for the Long Wavelength Array (LWA) by the U.S. Naval Research Lab, the University of New Mexico, Virginia Tech, and the Jet Propulsion Laboratory. LoFASM, funded by the U.S. Department of Defense, will initially consist …

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Experimental Observation Of Lasing Shutdown Via Asymmetric Gain, M. Chitsazi, S. Factor, J. Schindler, Hamidreza Ramezani Apr 2014

Experimental Observation Of Lasing Shutdown Via Asymmetric Gain, M. Chitsazi, S. Factor, J. Schindler, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

Using a pair of coupled RLC cavities we experimentally demonstrate that amplification action can be tamed by a spatially inhomogeneous gain. Under specific conditions we observe the counterintuitive phenomenon of stabilization of the system even when the overall gain provided is increased. This behavior is directly related to lasing shutdown via asymmetric pumping, recently proposed in M. Liertzer et al. [Phys. Rev. Lett. 108, 173901 (2012)]. The analysis of other simple systems reveals the universal nature of the lasing shutdown phenomenon as having its roots in managing impedance matching.

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Fermi-Normal, Optical, And Wave-Synchronous Coordinates For Spacetime With A Plane Gravitational Wave, Malik Rakhmanov Apr 2014

Fermi-Normal, Optical, And Wave-Synchronous Coordinates For Spacetime With A Plane Gravitational Wave, Malik Rakhmanov

Physics & Astronomy Faculty Publications

Fermi-normal (FN) coordinates provide a standardized way to describe the effects of gravitation from the point of view of an inertial observer. These coordinates have always been introduced via perturbation expansions and were usually limited to distances much less than the characteristic length scale set by the curvature of spacetime. For a plane gravitational wave this scale is given by its wavelength which defines the domain of validity for these coordinates known as the long-wavelength regime. The symmetry of this spacetime, however, allows us to extend FN coordinates far beyond the long-wavelength regime. Here we present an explicit construction for …

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Gravitational Wave Hotspots: Ranking Potential Locations Of Single-Source Gravitational Wave Emission, Joseph Simon, Abigail Polin, Andrea Lommen, Ben Stappers, Lee Samuel Finn, F. A. Jenet, B. Christy Mar 2014

Gravitational Wave Hotspots: Ranking Potential Locations Of Single-Source Gravitational Wave Emission, Joseph Simon, Abigail Polin, Andrea Lommen, Ben Stappers, Lee Samuel Finn, F. A. Jenet, B. Christy

Physics & Astronomy Faculty Publications

The steadily improving sensitivity of pulsar timing arrays (PTAs) suggests that gravitational waves (GWs) from supermassive black hole binary (SMBHB) systems in the nearby universe will be detectable sometime during the next decade. Currently, PTAs assume an equal probability of detection from every sky position, but as evidence grows for a non-isotropic distribution of sources, is there a most likely sky position for a detectable single source of GWs? In this paper, a collection of Galactic catalogs is used to calculate various metrics related to the detectability of a single GW source resolvable above a GW background, assuming that every …

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Concept Of A Reflective Power Limiter Based On Nonlinear Localized Modes, Elena Makri, Hamidreza Ramezani, Tsampikos Kottos, Ilya Vitebsky Mar 2014

Concept Of A Reflective Power Limiter Based On Nonlinear Localized Modes, Elena Makri, Hamidreza Ramezani, Tsampikos Kottos, Ilya Vitebsky

Physics & Astronomy Faculty Publications

Optical limiters are designed to transmit low-intensity light, while blocking the light with excessively high intensity. A typical passive limiter absorbs excessive electromagnetic energy, which can cause its overheating and destruction. We propose the concept of a photonic reflective limiter based on resonance transmission via a localized mode. Such a limiter does not absorb the high-level radiation, but rather reflects it back to space. Importantly, the nearly total reflection occurs within a broad frequency range and direction of incidence. The same concept can be applied to infrared and microwave frequencies.

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Minisuperspace Canonical Quantization Of The Reissner-Nordström Black Hole Via Conditional Symmetries, T. Christodoulakis, Nicholas Dimakis, Petros A. Terzis, Babak Vakili, E. Melas, Th. Grammenos Feb 2014

Minisuperspace Canonical Quantization Of The Reissner-Nordström Black Hole Via Conditional Symmetries, T. Christodoulakis, Nicholas Dimakis, Petros A. Terzis, Babak Vakili, E. Melas, Th. Grammenos

Physics & Astronomy Faculty Publications

We use the conditional symmetry approach to study the r evolution of a minisuperspace spherically symmetric model both at the classical and the quantum level. After integration of the coordinates t, θ and ϕ in the gravitational plus electromagnetic action the configuration space dependent dynamical variables turn out to correspond to the r-dependent metric functions and the electrostatic field. In the context of the formalism for constrained systems (Dirac-Bergmann, Arnowitt-Deser-Misner) with respect to the radial coordinate r, we set up a pointlike reparametrization invariant Lagrangian. It is seen that, in the constant potential parametrization of the lapse, the corresponding minisuperspace …

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First Searches For Optical Counterparts To Gravitational-Wave Candidate Events, M. Constancio, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Feb 2014

First Searches For Optical Counterparts To Gravitational-Wave Candidate Events, M. Constancio, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers …

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Searching For Pulsars Using Image Pattern Recognition, W. W. Zhu, Kevin Stovall, Stephanie Cohen, Louis Percy Dartez, Grady Lunsford, Jose Guadalupe Martinez, Alberto Mata, Fredrick A. Jenet Feb 2014

Searching For Pulsars Using Image Pattern Recognition, W. W. Zhu, Kevin Stovall, Stephanie Cohen, Louis Percy Dartez, Grady Lunsford, Jose Guadalupe Martinez, Alberto Mata, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

In the modern era of big data, many fields of astronomy are generating huge volumes of data, the analysis of which can sometimes be the limiting factor in research. Fortunately, computer scientists have developed powerful data-mining techniques that can be applied to various fields. In this paper, we present a novel artificial intelligence (AI) program that identifies pulsars from recent surveys by using image pattern recognition with deep neural nets - the PICS (Pulsar Image-based Classification System) AI. The AI mimics human experts and distinguishes pulsars from noise and interference by looking for patterns from candidate plots. Different from other …

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Self-Heating Model Of Spherical Aluminum Nanoparticle Oxidation, Karen S. Martirosyan, Zamart Ramazanova, Maxim Zyskin Jan 2014

Self-Heating Model Of Spherical Aluminum Nanoparticle Oxidation, Karen S. Martirosyan, Zamart Ramazanova, Maxim Zyskin

Physics & Astronomy Faculty Publications

Aluminum-oxygen reaction is important in highly energetic and high pressure generating systems. Nanoenergetic thermites include mixtures of nanostructured Al and oxidizer particles. The main distinguishing features of these reactive systems are their significant enthalpy release and tunable rate of energy discharge, which gives rise to a wide range of combustion rates, energy release, and ignition sensitivity. In this paper, we consider rapid oxidation of a spherically symmetric aluminum particle. We use the Cabrera Mott oxidation model to describe the kinetics of oxide growth of an aluminum nanoparticle and to predict reaction temperature and oxidation time. We assume that aluminum particle …

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Application Of A Hough Search For Continuous Gravitational Waves On Data From The Fifth Ligo Science Run, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, A. S. Stroeer, Lappoon R. Tang, Cristina V. Torres Jan 2014

Application Of A Hough Search For Continuous Gravitational Waves On Data From The Fifth Ligo Science Run, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, A. S. Stroeer, Lappoon R. Tang, Cristina V. Torres

Physics & Astronomy Faculty Publications

We report on an all-sky search for periodic gravitational waves in the frequency range 50–1000 Hz with the first derivative of frequency in the range −8.9 × 10−10 Hz s−1 to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a χ2 test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present …

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Unidirectional Lasing Emerging From Frozen Light In Nonreciprocal Cavities, Hamidreza Ramezani, S. Kalish, I. Vitebskiy, T. Kottos Jan 2014

Unidirectional Lasing Emerging From Frozen Light In Nonreciprocal Cavities, Hamidreza Ramezani, S. Kalish, I. Vitebskiy, T. Kottos

Physics & Astronomy Faculty Publications

We introduce a class of unidirectional lasing modes associated with the frozen mode regime of nonreciprocal slow-wave structures. Such asymmetric modes can only exist in cavities with broken timereversal and space inversion symmetries. Their lasing frequency coincides with a spectral stationary inflection point of the underlying passive structure and is virtually independent of its size. These unidirectional lasers can be indispensable components of photonic integrated circuitry.

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